The hydrothermal synthesis, properties and application of functional xCaO·y(Al2O3, SiO2)·zH2O compounds ; Funkcinių xCaO·y(Al2O3, SiO2)·zH2O junginių hidroterminė sintezė, jų savybės ir taikymas

Hydrothermal synthesis of xCaO·y(Al2O3, SiO2)·zH2O compounds in the CaO-Al2O3-SiO2-H2O system is a complex process. The formation of compounds in this system are determined by the duration of isothermal treatment, temperature and composition of the initial mixture. Therefore, it is important to examine the influence of synthesis conditions on the formation and properties of functional xCaO·y(Al2O3, SiO2)·zH2O compounds. In this work it was determined that hydrogranates which usually form during hydrothermal synthesis in CaO, SiO2 and Al2O3 suspensions may not be obtained in this system, and only calcium hydroaluminates and calcium hydroalumosilicates may dominate in the products. It was revealed that the synthetic calcium hydroalumosilicate additive changes the hydration of cement samples and accelerates the curing process: it shortens the induction period, stimulates the hydration of C3S and increases the total amount of heat released. It was determined that synthetic mayenite additive, which stabilizes the natural CaO chemosorbent in the cyclic CO2 adsorption/desorption process, can be obtained at 350°C temperature by burning hydrothermally treated calcium hydroalumosilicate. According to the obtained results, conclusions, recommendations and the rational application areas of the above mentioned synthetic calcium hydroalumosilicate additive were proposed.